High frequency oscillators may be used to generate clocks for electronic circuits. High frequency oscillators, for example, may be used for spread spectrum clock generation. Some example electronic circuits that may use such clock generation include integrated circuits (ICs), which may be used to implement, for example, systems-on-a-chip, processors, and chipset chips. Spread spectrum clock generation techniques may reduce adverse effects of electro-magnetic interference (EMI).
Spread spectrum clock generation techniques may use variable frequencies that vary between a maximum frequency value and a minimum frequency value to generate different oscillator wave forms such as sine waves, triangle waves, or other shaped waves. Spread spectrum clock generation may be performed using a phase-locked loop (PLL), such as by modulating a voltage controlled oscillator (VCO) control voltage or by modulating a feedback divider ratio.